Megalooikonomou, Konstantinos G.

Plastic Hinge Length in Columns - Definition Through Consideration of Yield Penetration Effects

Abstract eng:
The plastic hinge length is defined as the length over a seismically swaying column, where flexural moments exceed the yielding capacity. This length, measured from the critical section towards the shear span, signifies the region where intense inelasticity occurs during the earthquake, and is determined in design codes through calibrated empirical relationships that account primarily for the length of the shear span and the diameter of primary reinforcing bars. The latter is meant to account in a simplistic manner for the effects of bar yielding penetration from the critical section towards both the shear span and the support of columns. Contrary to the fixed design values adopted by codes of assessment, a consistent definition of the notion of the plastic hinge length is with reference to the actual state of reinforcement – as the length over which bar strains exceed yielding. Note that the development of flexural yielding and large rotation ductilities in the plastic hinge zones of frame members is essentially synonymous with the spread of bar reinforcement yielding. Yield penetration in the anchored reinforcing bar inside the shear span of the column where it occurs, destroys interfacial bond between bar and concrete and reduces the strain development capacity of the reinforcement. This affects the plastic rotation of the member by increasing the contribution of bar slippage. In order to establish the plastic hinge length in a manner consistent to the above definition, this paper pursues the explicit solution of the field equations of bond over the shear span of a column. Through this approach, the bar strain distributions and the extent of yield penetration from the yielding cross section towards the shear span are resolved and calculated analytically. By obtaining this solution the aim is to establish a consistent definition of plastic hinge length and to illustrate the true parametric sensitivities of this design variable for practical use in seismic assessment of existing structures. Results obtained from the analytical procedures are compared with data from selected tests on reinforced concrete columns under seismic loading reported in the literature.

Contributors:

Pantazopoulou, Stavroula J.

Conference Title:

Proceedings of the 16th World Conference on Earthquake Engineering

Conference Title:

16th World Conference on Earthquake Engineering

Conference Venue:

Santiago (CL)

Conference Dates:

2017-01-09 / 2017-01-13

Rights:

Text je chráněný podle autorského zákona č. 121/2000 Sb.